Gregory Corso, who has died aged 70, was the bad boy of the beat generation. In 1957, he wrote to Allen Ginsberg from Paris to complain that a man who had allowed him to stay in his flat "came back from his vacation and screamed at me when he saw that I did beautiful oil paintings on his walls and doors". The injured landlord, Corso added, told Jean Genet what he had done, which brought a telling-off from the poet-thief. Genet, Corso concluded, "is so fucking bourgeois".

Corso was born to Italian parents in Greenwich Village, New York. Before he was one, his mother abandoned him, and he spent his childhood shuttling between orphanages, reform schools and foster homes, occasionally being rescued by his hopeless father, from whom he tried to escape.

By the time he reached his teens, he had been in the children's observation ward at Bellevue hospital and spent five months in the Tombs jail as a material witness to a robbery. At 16, he began a three-year sentence at Clinton state prison, New York, for robbing a household finance office. There, in the classic conversion hitherto experienced by his adversary Genet, he discovered poetry.

"Open this book as you would a box of toys," Ginsberg wrote in a preface to Corso's second volume of poems, Gasoline, published by Lawrence Ferlinghetti's City Lights Books in 1958. It was dedicated to "the angels of Clinton prison who, in my 17th year, handed me, from all the cells surrounding me, books of illumination".

Corso's introduction to the other beats came through Ginsberg, whom he met in a New York bar in 1950. Corso told his new friend that, from his window, he was in the habit of watching a couple in the flat opposite as they undressed, bathed and made love. Later, when Ginsberg invited him to meet his girlfriend, Corso realised that this was the couple he had been watching.

Attracted not only to Corso's good looks - Ginsberg was bisexual - and his delinquent background, but also by the sheaf of poems he carried everywhere, Ginsberg welcomed Corso into his circle, introducing him to Jack Kerouac and William Burroughs, and later to the San Francisco poets. Their life of camaraderie and occasional tension is described in Kerouac's novels, The Subterraneans and Desolation Angels. In the former, written in 1953 but not published until five years later, the Kerouac-figure Leo breaks with his girlfriend, Mardou, after discovering she has been sleeping with Corso (Yuri Gligoric).

After the succès de scandale of Ginsberg's book Howl in 1957 (the poem was prosecuted in San Francisco, but cleared of obscenity) and the publication of Kerouac's On the Road the same year, Corso became part of the travelling circus of beat poets, which usually comprised himself, Ginsberg and Peter Orlovsky.

In response to a member of the audience asking, "What's the message of your poetry?", Ginsberg might strip off his clothes; or Corso would say, "Fried shoes" or "Poetry is a wose." Orlovsky would read two poems, then say he would love to do the third but he had not written it yet. It was the moment when long hair and the philosophy of the unwashed became emblematic of youth's crusade for freedom.

In the late 1950s, the same trio lived together in Paris, in what came to be known as the Beat Hotel, in rue Git-le-coeur, near St Michel. For a time, they all slept in the same bed, but eventually Corso found his own room on the top floor, a triangle barely high enough to let him stand up, or wide enough to contain him sleeping. His novel, The American Express, was published by Olympia Press in 1961, and he took part in the original book of cut-ups, Minutes To Go, with Burroughs, Brion Gysin and Sinclair Beiles.

Corso's best poetry was metaphysical, in the sense that it recognised no frontier between spirit and matter. But Ginsberg was right; the poem was a place for him to play. Corso talked to Truth (who replied, "I'll tell awful things about you"), talked to Faith, Hope and Charity ("'Without us you'll surely die/ With you I'm going nuts! Goodbye!") and to Beauty ("You I loved best in life/ . . . but you're a killer").

Occasionally, as in the elegy for Kerouac in his 1970 collection, Elegiac Feelings American, he tried to use the long, Whitmanesque line so successfully employed by some beat colleagues, but he could not fill it. A promising start, "How alien the natural home, aye, aye, how dies the tree," would plunge into bathos before the end of the phrase, "when the ground is foreign, cold, unfree".

The poets he loved most were not the moderns, but the English romantics, in particular Keats and Shelley, and the ancients. Like many anti-academy poets of the postwar years, Corso was sucked into university in later life. One student left a record of a class with him at New York University. For the first 15 minutes, he berated them for their ignorance of Greek classics: "I find somebody dumb who doesn't know Homer - that's how I feel. Check him out. He brought the Greek gods on the scene, that is for sure. But then again, we don't have to be stuck with the Iliad . . ." He rocks in his chair and checks his wrist for a non-existent watch. "How long have I been here?" "Twenty minutes." "That's a long time, man!"

Although teaching was a way to make a living, Corso never stayed at any one college for long. Nor did he like doing live readings. Heavy drug use in the 1960s and 70s meant that the poverty of his youth continued. When an interviewer inquired about the state of his finances in 1974, he revealed that when he needed money for drugs he would sell one of his poetry notebooks. "I get about $200 a book," he said. "So a lot of my poems are in the universities and have never been published." But, he added, "the goodies I remember in my head".

Among the many other books and pamphlets he did publish were The Happy Birthday Of Death (1960), The Geometric Poem (1966) and Herald Of the Autochthonic Spirit (1981). A Selected Poems was issued in Britain by Eyre and Spottiswoode in 1962, but like other beat poets, such as Gary Snyder and Ferlinghetti, Corso has been neglected by British publishers.

When young, Corso's looks were often described as "cherubic", but in later life, with teeth missing and hair uncombed, there was more than a touch of the gargoyle about him. "Mainly I sleep with my cats and the female," he once said, describing his domestic situation. "I love female. I've been with this one female now for a year." One of Ginsberg's later photographs shows him at home with "the female" (Kay MacDonagh) and their baby, and quotes a few lines from one of Corso's most famous poems, Marriage (1959): "and she gives birth to a child and I am sleepless, worn,/ up for nights, head bowed against a quiet window, the past behind me..."

But he remained the bad boy. One British poet, meeting Corso in the 1980s, was startled when he began to exhibit objects stolen from houses where he had been staying. The same observer noticed how Ginsberg watched over his old friend as if he were a child, making sure he had something to do in the evenings, while the "grown-up" poets met to eat and talk in restaurants.

Yet Corso never forgot his debt to poetry, often talking about his muse as if she were sitting next to him. In interviews with academics, he never tried to change his direction or tone, staying true to the ebullient kid who had learned how to live on the street and how to write in prison. Sometimes, it was hard to tell whether he was having a joke or not:

Interviewer: "Do you know other languages?"

Corso: "Ancient Egyptian. Not much spoken today."

His third marriage, to Sally November, ended in divorce. He is survived by his second wife, Belle Carpenter, three daughters, two sons, his mother, a brother, seven grandchildren and a great-grandchild.

 Gregorio Nunzio Corso, poet and writer, born March 26 1930; died January 17 2001